Engine



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INVENTOR- BY my 20;

ATTORNEY J. DOLZA Dec. 6, 1960 ENGINE Original Filed Jan. 19, 1955 D 6,1960 I J. DOLZA 2,963,009

ENGINE Original Filed Jan. 19, 1955 2 Shee She 2 ATTORNEY United StatesPatent 2,963,009 ENGINE John Dolza, Fenton; Mich, assiguor to GeneralMotors Corporation, Detroit, Mich,- a corporation of Delaware Originalapplication Jan. '19, 1955, Ser. No. 482,79,

now Patent No. 2,865,341, datedDec. 23, 1958. D1- vided and thisapplication July 22, 1957, Ser. No. 673,434

The present invention relates to engines and more particularly tointernal combustion engines. This application is a division ofSerialNo.v 482,794 filed January 19, 1955, now Patent No. 2,865,341, inthe name of John Dolza. V

In the past internal combustion engines have employed a single castingthat forms a cylinder block having one or more cylindrical passagesextending therethrough. Pistons are then disposed in these cylinders andone or more cylinder heads may be secured to the cylinder block forclosing the open ends of the cylinders and also cooperate with the upperends of the pistons to form combustion chambers. The opposite ends ofthe cylinders may open into a crankcase that is formed by a recessextending longitudinally along the bottom of the block. A sheet metalpan is then normally secured to the block to form a crankcase thatencloses a rotating crankshaft driven by the pistons. A plurality ofbulkheads on the block may then extend transversely across the recess todivide it into one or more compartments. Bearing caps are secured to thebottoms of these bulkheads to cooperate with recesses in the bulkheadsand form the main bearings for supporting the crankshaft. Although thisform of construction has been satisfactory in the past, there are manyobjections thereto when it is employed in a high compression lightweightengine. For instance, this requires excessively heavy castings, theengine is not a basically rigid mounting for the crankshaft, it isdifficult to assemble and it is not well adapted for lightweight alloys.

It is now proposed to provide an engine in which the cylinder blockincludes an upper member and a lower member which may be cast so eachone is in and (liltself very rigid. Thus when they are secured together,they will form an integral structure which is very rigid. The uppermember may have a pluralityof cylinder passages extending therethroughso the inner ends open into a recess extending along one of the sides ofthis block. A plurality of transverse bulkheads may extend across thisrecess to divide it into separate compartments. The lower member mayhave a longitudinally extending recess similar in shape to that in theupper member with bulkheads also dividing it into separatecompartments.The bulkheads on the two members may be positioned so that the bulkheadson one member will be in the same plane as those on'the other member sothat the adjacent bulkheads will have abutting edges.

The upper and lower members are preferably sepa rated along a planeincluding the axis of the crankshaft. Thus the abutting edges of thebulkheadsmay have a semi-cylindrical bearing. When the two members aresecured together, the semi-cylindrical bearings will form the mainbearings for the crankshaft arid these recesses will form a crankcasefor enclosing a crankshaft. It will thus be seen that each of themembers may be a rigid box-like structure reinforced by transversebulkheads. Consequently, when both of themembers are secured together,they will form a very rigid structure that will maintain the crankshaftproperly positioned at all times. If desired, an opening may be providedin the bottom of the lower member to allow excess lubricants to flowfrom the crankcase. A stamped sheet metal pan may be secured to thelower member to close this opening and form a sump for the enginelubricant. When the engine is to be employed in an automobile in whichroad clearance is a problem, the opening may be confined to the higherend of the engine so that the downwardly projecting pan will notmaterially lower the road clearance.

The cylinder heads and the intake manifold heretofore have comprisedseveral separate pieces. This is particularly true in so-called V-typeengines in which a separate cylinder head is usually provided for eachbank of cylinders and an intake manifold is disposed therebetween.Heretofore, each of these members have been separately handled andindividually assembled onto the engine, thus presenting numerousproblems in sealing and securing the members together. In addition,since there are several members, there may be relative movement betweenthe banks of cylinders. As a result there have been numerous attempts todevise an integral cylinder head and manifold structure especially forV-type engines that will reinforce the engine and also simplifymanufacturing. However, to date, these structures have resulted incomplex structures that present numerous manufacturing problems suchasrequiring complicated coring, etc.

It is now proposed to provide a cylinder head and intake manifoldassembly which incorporates the advantages of a one piece cylinder headand manifold structure without being subjected to all of theproblemsinvolved in the manufacture of the previous structures. This structureis especially adapted for use on V-type engines and it includes a lowermember and an upper member. The lower member includes a pair ofangularly disposed faces that are adapted to seat on similarly disposedsurfaces on the cylinder block. This lower member will thereby extendall the way across the top of the engine to act with the cylinder banksto form a rigid triangular structure. These faces are also adapted toclose the upper ends of the cylinders and thus form the combustionchambers. The intake and exhaust valves may be mounted on the headportions of the lower member so that they may be preassembled thereon.The upper member may include mountings for the Valve actuating meanssuch as the camshafts, rocker arms, etc., so that they may bepreassembled thereon. Both the upper and lower members may includemating recesses that are adapted to cooperate in forming the inductionpassages when they are secured together. It may thus be seen that asimplified head and manifold structure has been provided which will actas a structural member in rigidifying the engine structure.

It should also be noted that since the induction passages are formed bymating recesses, the recesses will be open and allow the use ofsimplified coring when casting these members. It may be seen that thissimplified coring of the parts will allow the use of any form ofmanifolding desired.

The induction system may include one or more longitudinally extendingducts that project forward from the engine so as to form one or moreinlets. These inlets may be positioned to take advantage of the ramming.

the present instance the invention is adapted for use on a V-type engineand so there are separate compartments disposed on the opposite sides ofthe engine. Each of these compartments is connected to the cylinders onthe opposite side of the engine by means of ram pipes. These ram pipesextend transversely of the engine and are tuned to resonate at someparticular engine speed. If desired, suitable air cleaning means may beemployed for cleaning the air before it enters the combustion chamber.In the present instance this includes air filter elements in thecompartments and on the intakes.

In the two sheets of drawings:

Figure 1 is a transverse cross sectional view of an engine embodying thepresent invention.

Figure 2 is a longitudinal cross sectional view of the engine ofFigure 1. V

Figure 3 is a fragmentary side elevational view of the engine disclosedby Figures 1 and 2 and having parts of the structure broken away andshown in cross section.

Referring to the drawings in more detail, the present invention may beembodied in any suitable engine 10. In the present instance this engine10 is of the so-called V-type having a cylinder block 12 and a head andmanifold assembly 14. The block 12 may include an upper member 16 and alower member 18. The upper member 16 may include two banks 20 and 22 ofaligned cylinders 1, 2, 3, 4, and 6. The axes of these cylinders aredownwardly convergent to intersect along an axis 24 extendinglongitudinally along the bottom of the upper member 16. The cylinders ineach bank 20 or 22 may extend diagonally through the upper member 16 toform a series of openings 26 in the plane surfaces 28 extending aboveeach bank 20 and 22 of cylinders along the opposite edges of the uppermember 16. A longitudinally extending recess 30 may be provided in thebottom of the upper member 16 so that the mouth of this recess 30 willform a mounting flange 32. The lower ends of the cylinders may open intothis recess 30.

The lower member 18 may also include a recess 34 and is adapted to besecured to the flange 32 on the bottom of the upper member 16. Therecess 34 in the lower member 18 may be similar in shape to that in theupper member 16 and be positioned to register therewith to form acrankcase 36.

A plurality of bulkheads 38, 40, 42 and 44 may be provided on the uppermember 16 and bulkheads 46, 48, 50 and 52 on the lower member 18 toextend transversely of the crankcase 36 and divide it into one or morecompartments. The bulkheads on one member may be disposed coplanar witha bulkhead on the other member so they will have abutting edges 37. Eachpair of these abutting edges may be provided with registeringsemicylindrical recesses 54. These recesses 54 are adapted to receivesuitable bearing inserts 56 to form a plurality of substantiallycylindrical main bearings 57 concentric with the axis 24.

An opening 58 may be provided in the bottom of the lower member 18 toallow any excess lubricant that may collect in the crankcase 36 to draintherethrough. A stamped sheet metal oil pan 60 may be secured to thebottom of the lower member 18 to close this opening 58 and collect thelubricant draining through the opening and thereby form a sump. Althoughthe entire bottom of the lower member 18 may be open, it has been foundthat by confining the opening 58 to the higher end of the engine 10, theoil pan 60 will not have to extend the fu11 length of the engine. Thusif the downwardly proecting oil pan is confined to the higher end of theengine and the engine is employed in an automotive vehicle, the roadclearance will be increased.

Any suitable crankshaft 62 may be disposed in the crankcase 36 so as tobe supported on the main bearings 57 for rotation about the axis 24. Inthe present instance this crankshaft 62 employs three pairs of throws 64which are separated by main journals 66 riding on the bearings 57 in thebulkheads. The throws 64 in each pair are disposed at 60 to each other.The pairs of throws are angularly disposed with respect to each otherand the crankshaft is counterweighted to balance the primary forces andcouples and the, secondary forces. The rear intermediate bearing 57 hasshoulders to engage shoulders on the crankshaft and oppose any axialthrust which may be imposed on the crankshaft 62.

The after end of the crankshaft 62 may be provided with a timing gear 68and a flywheel 70 or other means suitable for connection to a load suchas a vehicle transmission or drive shaft. The forward end of thecrankshaft 62 which is supported by the bearing 57 may project throughthe forward bulkheads 38 and 46 and through a housing 71 secured to theexterior of the forward bulkheads. A seal 72 may be provided in thefront end of this housing 71 so as to be in wiping contact with thecrankshaft 62 and prevent the loss of any lubricants from the crankcase36. A viscous type torsional vibration dampener 74 may be secured to thefront end of the crankshaft 62 for absorbing any such vibrations in thecrankshaft 62. The lubricant may be circulated through the engine bymeans of a gear type pump 76 which is disposed in the housing 71. Thispump 76 may include a drive gear 78 and a pair of planetary gears 70 and82 that are mounted on the pins 84. This pump 76 may include a drivegear 78 and a pair of planetary gears 80 and 82 that are mounted on thepins 84. This pump 76 may include a single inlet in the sump and twoseparate outlets. Thus the pump may draw lubricant from the sump anddischarge the lubricant from one outlet into the engine lubricatingsystem and from the other outlet into the transmission. A drive pulley83 may also be provided on the end of the crankshaft.

A lubricant cooler may be provided on the cylinder block for cooling theoil before it is returned to the lubricating system or the transmission.The present cooler is disposed in heat exchanging relation with theengine cooling system adjacent the point where the coolant enters theblock 12 and is coolest to provide the most effective cooling of thelubricant. If desired, this cooler may carry the entire amount of oilflowing through the pump 76 and thus cool all of the lubricant flowingto both the engine and transmission.

Each of the cylinders may have a piston 86 of suitable design disposedtherein. In the present instance the pistons 86 are of the so-calledslipper type having a skirt 88 and a domed head 90 that has a surfaceadapted to form a portion of the combustion chamber Wall. A pair ofdiametrically aligned pin bosses 92 may be provided in the skirts 88 forreceiving the opposite ends of wrist pins 94. The centers of the wristpins 94 may receive a bearing in the upper ends of the connecting rods96 which have the lower ends thereof secured to journals on the variousthrows of the crankshaft 62. In order to seal the clearance spacesprovided between the pistons 86 and cylinder walls, each piston 86 mayhave a pair of compression rings 98 seated in annular grooves extendingaround the upper end of the skirt 88. These compression rings 98 arepreferably disposed between the upper end of the piston 86 and the wristpin 94. In addition, an oil ring 100 may be provided on the lower end ofthe skirt 88 for wiping excess oil off of the cylinder walls. This oilring 100 is preferably disposed below the wrist pin 94.

The head and manifold assembly 14 may be provided on top of the engine10 so as to extend the full width thereof. This assembly 14 includes anupper member 101 and a lower member 102 having a center portion 104 anda pair of angularly disposed head portions 106 and 108 on the oppositesides thereof. These head portions 106 and 108 may include plane faces110 and 112 that seat on the plane surfaces 28 on the upper sides of thecylinder block 12. These faces 110 and 112 will close the open ends ofthe cylinders and together with the upper ends 96 of the pistons 66 willform the combustion chamber. If the plane surfaces 28 on the block 12are oblique to the axis of the cylinders, the angle between the twofaces may be materially decreased. This in turn may reduce problems inthe manufacturing of the lower member that might result in machining thefaces and/ or warping of the member. In addition the entire combustionchamber will be contained inside of the cylinders.

The upper end of each piston 86 may include a pair of angularly disposedplane surfaces 114 and 116. One of these surfaces 114 on each piston 86is preferably substantially parallel to a face 110 or 112 of the headportion 106 or 108 while the other surface 116 may be angularly disposedwith respect thereto. It will thus be seen that when the piston 86approaches top dead center, there will be a thin quench or squish zone115 formed between the face 110 or 112 and surface 116' and a compactfiring zone 117. As a result when the piston 86 is traveling upwardly,the gases in the squish zone will be more rapidly compressed than thosein the firing zone and consequently, there will be a blast of gases thatwill flow from the squish zone into the firing zone thereby creating avery turbulent flow of gases in the firing zone.

The intake and exhaust valves 118 and 120 which control the ingress andegress of gases into and out of the cylinder may be disposed in the headportions 106 and 108. In the present instance the valves 118 and 120 arereciprocably disposed in valve guides that extend through the headportions of the lower member 102 so that the valve stems 122 and 124will project from the top of the lower member 102. Cup shaped springseats may be provided on the upper ends of the stems 122 and 124 so thatone or more springs 126 may bias the valves 118 and 120 closed. Thuswhen the valves 118 and 120 are mounted on the lower member 102 theywill be secured in position to allow the lower member to be handled as asingle unit.

The intake valve 118 allows air to flow through the induction systemdirectly into the combustion chamber where the fuel is sprayed into theair by meansof a nozzle 128. This nozzle 128 may be screwed into athreaded passage that extends through the block to form an opening inone of the cylinder walls. Thus the nozzle 128 may spray fuel into thefiring zone where it will mix with the air therein. The fuel is suppliedto this nozzle 128 by means of a tube 132 which communicates with a fuelpumping and metering mechanism. In order to ignite the charge formed inthe chamber, a spark plug 134 may be threadably mounted in the headportion 106 or 108 so that the electrodes will be disposed in a pocket136 communicating with the firing zone. Thus when a discharge occursacross the spark plug electrodes, the charge will be ignited in thecompact firing zone. A large majority of the charge will be rapidlyburned in this space 117 which has a large volume-to-surface ratio.After this is completed the end gases will be burned in the quench zone115 formed between the piston 86 and the head 166 and 108. This quenchzone 115 may have a very large surface-to-volume ratio that will tend toabsorb heat from the unburned end gases and prevent premature ignitionthereof.

A valve actuating mechanism may be provided for opening and closing theintake and exhaust valves and thereby control the flow of gases into andout of the combustion chamber. In the present instance the oppositesides of the upper member 101 may include camshaft galleries 140 and 142that extend longitudinally of the engine above each bank 20 and 22 ofcylinders. A camshaft 144 and 146 may be rotatably mounted in bearings148 formed in each gallery so' as to extend the length of the gallery140and 142. A plurality of rocker arms 149 and 150 may be pivotallymounted on the upper member 101 so as to extend transversely of thecamshaft gallery 140 and 142 so that the middle of each rocker arm willride on one of the cams 152. Since all of the intake and'exh'austvalve's 118' and are not'disp'o'se'd in a common plane, the rocker arms149 for' the intake valves 118'are pivoted on one side of the galleryand 142 and those for the exhaust valves 120 are pivoted on the oppositeside so that the ends thereof will engage the ends of the valve stems122 and 124. 'It can thus be seen that when the rocker arms 149 and 150and camshaft are mounted on'the upper member 10-1, this assembly 14 canbe handled as a single member.

The rear end of each camshaft 144 and'146 may have a gear 154 mountedthereon which meshes with a gear train 156 driven from the timing gear68 at the rear end of the crankshaft 62. Thus rotation of the crankshaft62 will cause rotation of the camshafts 144 and 146 with a consequentopening and closing of the valves 118 and 120. Gallery covers 157 may besecured to the upper member 101 to close each gallery 140 and 142 andthereby conceal and protect the camshafts 144 and 146, etc., and also toprevent the loss of lubricants therefrom. In addition, a timing cover158 may be secured to the rear of the engine for enclosing the timinggear train 156.

The forward end of one camshaft 144 and 146 may project from the'frontof the engine 10 so as to drive a distributor 160 for timing theelectrical discharges through the spark plug electrodes. The forward endof the other camshaft 144 and 146 which is on the opposite side of theengine 10 may be adapted to drive the fuel pump for discharging fuelthrough the injector nozzles 128.

In order to deliver air to the cylinders, an induction system 162 may beprovided. In the present instance this system 162 includes a pair oflongitudinally extending ducts 164 which project forwardly from thefront of the engine 10 to form intakes. These intakes may be disposed onthe opposite sides of the engine and outside of the flow of hot airpassing through the radiator and fan. The rear ends of these ducts 164may enlarge and flatten out so as to form covers 166 that may be securedto the sides of the head and manifold assembly. Each of these covers 166may fit over a pair of communicating recesses 168 in the edges of theupper and lower members 101 and 102 to thereby form chambers 170 on theopposite sides of the engine. These chambers 171 may be interconnectedwith the various cylinders by means or" induction passages. In thepresent instance these induction passages form ram pipes 172 that extendfrom the chamber 170 on one side of the engine 10 to the cylinders inthe bank on the opposite side of the engine. If so desired theseram'pipes 172 may be shaped to resonate at some particular engineoperating condition. As a consequence when the engine 10 is operating atthis condition and the pipes 172 are resonating, there will be a rammingof the air into the cylinders which will tend to produce a superchargingof the engine. In addition the air flow may be such as to produce a veryhigh volumetric efficiency even though the engine 10 is not operating atthat particular condition.

Each of these ram pipes 172 are formed by a pair of registering recesses174 and 176 in the upper and lower members 101 and 102 respectively.When the members are secured together these recesses 174 and 176 will cooperate with each to define the walls of the pipes 172. The outer endsof these pipes form openings in the sides of the recesses 168 so as tocommunicate with one of the chambers 170 and the inner ends from theseats for the intake valves 118. It should be noted that these recesses168, when the upper and lower members 1111 and 102 are separated, oneside thereof will be open to the atmosphere and will thus permit aconsiderably simpler coring arrangement thereby reducing the cost ofmanufacture and enabling a freer choice of manifold designs.

In order to control the flow of air into the engine, a throttle valvemay be disposed in each of the intakes so as to rotate about the axis ofa shaft. These shafts may have an arm that is connected to a linkageextending along the outer sides of the cylinder banks. This linkage maybe connected to a cross shaft that extends across the back of the engineand is actuated by a common accelerator control. Although the linkagemay be adapted to adjust the relative positions of the throttle valves,there may be structural variations or other means that will producedifferences in the amount of air flowing into the two separate chambers.As a result a balance tube 180 may extend around the rear end of theengine 10 to allow a balancing of the air in the two chambers 170.

In order to prevent any foreign matter in the atmosphere entering theengine, air cleaners may be provided on the intakes and/or filterelements 182 may be disposed inside of the chambers. These elements 132may divide the chambers 170 into inner and outer compartments 184 and186 with the air entering the outer compartment 186 and leaving from theinner compartment 184. The inner compartment 184 may enclose the sparkplugs 134.

An exhaust system may be provided for discharging the exhaust gases fromthe combustion chambers into the atmosphere. This system may include anexhaust passage 200 for each cylinder that will extend from the exhaustvalve 120 outwardly through the head portions 106 and 108 to formexhaust ports 202 in the outsides of the head portions. The outerportion 204 of each exhaust passage may be relieved to receive the endof an exhaust pipe 206 that will extend through the exhaust port 202.This will allow the interior of the exhaust pipes to be in substantialalignment with the interior of the exhaust passage and thereby form asmooth streamline continuation thereof. A collar 208 may be provided onthe exterior of the exhaust pipe 206 to form a flange that can besecured to the exterior of the head member. The exhaust pipes 206 fromeach bank and 22 may converge into a common chamber. Each of thesechambers may in turn be connected to a muffler for silencing the exhaustgases before they are discharged into the atmosphere.

In order to obtain the maximum discharge of exhaust gases from thecylinder, it has been found advantageous to shape the exhaust pipes sothat they will resonate at some engine operating condition. Thus if theengine is operating at this condition and these pipes resonate, thesurging of the gases will tend to produce a vacuum adjacent the exhaustvalves which will greatly improve the discharge of the exhaust gasesfrom the cylinder.

In order to prevent overheating of the various parts of the engine acooling system may be provided. In the present instance this systemincludes a cooling jacket 210 that is disposed in heat exchangingrelation with the walls of the cylinders and the walls of the combustionchamber. In addition the jacket 210 may include passages 212 thatpermeate the head and manifold assembly 14 so as to be in intimate heatexchanging relation with the valve seats and the walls of the ram pipes172. A coolant pump 214 may be provided for forcing the coolant throughthe various passages in the cooling jacket. This pump 214 may include ahousing 216 and an impeller 218 which is carried on a rotating shaft 220that projects from the front end of the housing. In the present instancethis pump 214 is of the centrifugal type having a forwardly curved vane.Although the pump does not have a difliuser, an integrally cast rib inthe housing 216 prevents swirling of the coolant thereby reducing thecavitation effect. The outer end of the shaft 220 may be provided with apulley 222 which is driven by a belt on the lower pulley 83. If desireda cast fan 224 may be provided which has the hub bolted to the pulley222 so as to rotate therewith. A spinner 226 may be placed over the hubof the fan so as to provide a smooth surface and also conceal the bolts,etc. This pump may draw coolant from a radiator and discharge into thecooling system adjacent the oil cooler.

I claim:

1. An internal combustion engine comprising an engine frame including anengine block having a row of cylinders therein, a plurality of membersforming an engine head, said head being secured to said block andenclosing the ends of said cylinders and forming a part of said engineframe, an induction chamber formed in said head and within and betweencertain of said members, and induction passages formed in said head andconnecting said induction chamber to said cylinders, said inductionpassages also being formed in said head and within and between certainof said members, said induction chamber being formed within three ofsaid members, one of said three members being secured to the other twoand with each of said three members extending substantially throughoutthe length of said induction chamber.

2. An internal combustion engine comprising an engine frame including anengine block having a row of cylinders therein, a plurality of membersforming an engine head, said head being secured to said block andenclosing the ends of said cylinders and forming a part of said engineframe, an induction chamber formed in said head and Within and betweencertain of said members, and induction passages formed in said head andconnecting said induction chamber to said cylinders, said inductionpassages also being formed in said head and within and between certainof said members, said induction passages being formed between two ofsaid members with said two members extending lengthwise of saidinduction passages throughout a substantial part of the length of saidinduction passages, one of said members forming said head and beingsecured to said block and the other of said members being secured tosaid one member.

3. An internal combustion engine comprising an engine frame including anengine block having a row of cylinders therein, a plurality of membersforming an engine head, said head being secured to said block andenclosing the ends of said cylinders and forming a part of said engineframe, an induction system formed in said head and within said membersand comprising induction passages leading to said cylinders, an exhaustsystem formed in said head and within said members and comprisingexhaust passages leading to said cylinders, inlet and exhaust valves forsaid cylinders and controlling the communication of said cylinders withsaid passages, said valves being mounted in one of said members, andvalve operating mechanism mounted in the other of said members andoperating said valves, said member with said valves mounted thereinbeing secured to said block and said member with said valve operatingmechanism mounted therein being secured to said one member, saidinduction system including said induction passages being formed in andbetween said members.

4. An internal combustion engine comprising an engine frame including anengine block having angularly disposed rows of cylinders therein, aplurality of members forming engine head means, said head means beingsecured to said block and enclosing the ends of said cylinders andforming a part of said engine frame, said rows of cylinders beingdisposed in spaced and parallel relation in said block and beingenclosed by spaced parts of said head means, said members being innerand outer members secured together with one of said members engagingsaid block, a pair of induction chambers formed in said head means andbetween said inner and said outer head members, there being one of saidinduction chambers on each side of said head means and extending inparallel relation to said rows of cylinders, induction passages formedin said head means and between said inner and said outer head membersand extending transversely across said head means from said inductionchambers on the sides of said head means to the cylinders in said rowson the opposite sides of said head means, said induction passages eachextending across said head means from an induction chamber on one sideof said 9 head means to a cylinder on the opposite side of said headmeans, said induction chamber and said induction passages each beingformed in part by said inner member and said outer member.

5. An internal combustion engine comprising an engine frame including anengine block having angularly disposed rows of cylinders therein, aplurality of members forming engine head means, said head means beingsecured to said block and enclosing the ends of said cylinders andforming a part of said engine frame, one of said members forming saidhead means being secured to said block and the other being secured tosaid one member, an induction system formed in said head means andwithin said members and comprising induction passages leading to saidcylinders, an exhaust system formed in said head means and within saidmembers and comprising exhaust passages leading to said cylinders, inletand exhaust valves for said cylinders and controlling the communicationof said cylinders with said passages, said valves being mounted in saidone of said members secured to said block, and valve operating mechanismmounted in the other of said members and operating said valves, saidvalves and said valve operating mechanism being arranged in rows on eachside of said head means and in parallel relation to said rows ofcylinders, said members forming said head means being unitary membersextending between said rows of cylinders and said valves and valveoperating mechanisms for said rows of cylinders.

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